diff --git a/libvips/convolution/Makefile.am b/libvips/convolution/Makefile.am
index f069548c..a0d2e1ab 100644
--- a/libvips/convolution/Makefile.am
+++ b/libvips/convolution/Makefile.am
@@ -7,6 +7,7 @@ libconvolution_la_SOURCES = \
 	correlation.h \
 	conv.c \
 	convf.c \
+	convi.c \
 	convsep.c \
 	compass.c \
 	fastcor.c \
diff --git a/libvips/convolution/convi.c b/libvips/convolution/convi.c
index 22583c63..7b66148d 100644
--- a/libvips/convolution/convi.c
+++ b/libvips/convolution/convi.c
@@ -427,9 +427,10 @@ intize( VipsImage *in, VipsImage **out )
 
 	vips_image_set_double( *out, "scale", out_scale );
 	vips_image_set_double( *out, "offset", out_offset );
+
 	g_object_unref( t ); 
 
-	return( out );
+	return( 0 );
 }
 
 static int
diff --git a/libvips/convolution/convolution.c b/libvips/convolution/convolution.c
index 3908dc18..1e062f15 100644
--- a/libvips/convolution/convolution.c
+++ b/libvips/convolution/convolution.c
@@ -158,6 +158,7 @@ vips_convolution_operation_init( void )
 {
 	extern int vips_conv_get_type( void ); 
 	extern int vips_convf_get_type( void ); 
+	extern int vips_convi_get_type( void ); 
 	extern int vips_compass_get_type( void ); 
 	extern int vips_convsep_get_type( void ); 
 	extern int vips_fastcor_get_type( void ); 
@@ -167,6 +168,7 @@ vips_convolution_operation_init( void )
 
 	vips_conv_get_type(); 
 	vips_convf_get_type(); 
+	vips_convi_get_type(); 
 	vips_compass_get_type(); 
 	vips_convsep_get_type(); 
 	vips_fastcor_get_type(); 
diff --git a/libvips/include/vips/convolution.h b/libvips/include/vips/convolution.h
index 04ef153b..9e52656e 100644
--- a/libvips/include/vips/convolution.h
+++ b/libvips/include/vips/convolution.h
@@ -48,6 +48,8 @@ int vips_conv( VipsImage *in, VipsImage **out, VipsImage *mask, ... )
 	__attribute__((sentinel));
 int vips_convf( VipsImage *in, VipsImage **out, VipsImage *mask, ... )
 	__attribute__((sentinel));
+int vips_convi( VipsImage *in, VipsImage **out, VipsImage *mask, ... )
+	__attribute__((sentinel));
 int vips_compass( VipsImage *in, VipsImage **out, VipsImage *mask, ... )
 	__attribute__((sentinel));
 int vips_convsep( VipsImage *in, VipsImage **out, VipsImage *mask, ... )